Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

zone valves struggles to open, slam's closing.

there are 2- v8043f 1036 honeywell zone valves on my hydronic heating system.
one is for house heating the other is for domestic hot water.
when in house heating mode only, system runs fine.

when domestic hot water zone runs alone no problem, no noise opening and very little noise closing zone valve.

when house heating zone is in operation and the storage tank calls for hot water, domestic hot water zone valve struggles to open, (short burst of vibration in piping) , because circulation pump is already running. when temperature is reached and house still needing heat (pump running), domestic hot water zone valve slams closed causing rattling in pipes.

a water hammer suppression tube is installed and has about 2 1/2 ft of air cushion, and is charged.

just replaced internal parts of zone valve, (ball, swing arm, o ring) , as well as the upper operating head,
the old ball was worn out and leaking through.

now to my question: what relay switch should i use making my house heating the primary zone and the domestic water my secondary zone, also if possible one with a 10 or 15 second delay


  • James D. Arch
    James D. Arch Member Posts: 19
    PS: first, THANK YOU!!!!
    second , mfg and part number will be helpful.
    again, thank you,
  • markotah
    markotah Member Posts: 36
    Have you checked to make sure the zone valve is installed correctly with the flow? If it is installed against the flow you will have this issue
    Mark Eatherton
    HEATON Member Posts: 118
    Ditto- backwards will def b a prob. saw this many times
  • James D. Arch
    James D. Arch Member Posts: 19
    thanks for replying,
    flow arrow on valve is correct.....
    still perplexted???
  • TomS
    TomS Member Posts: 62
    The Honeywell valves are a fast closing valve and I think that this is causing your problem. If you take off the top cover of the valve you will see two springs. One is easy to get to and the other is kind of hidden. Unhook one end of the spring that is easy to get to. This will then allow the valve to slowly close and prevent the loud pipe rattle you hear on closing. If you don't like the results you can easily rehook the spring. Although I have not heard about the problem of the valve struggling to open I suspect that this fix might help in that regard also. Let us know how you make out.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    Check all the arrows on all the components (pump included).

    The first give away is the "struggles to open", statement, and the second is the BANG when closing, both indicators of something flowing water backwards. There is a (remote) possibility that the pump is significantly oversized, and when more than one zone is calling, that there is enough residual head at the end of the circuit to cause this problem, but it is extremely rare. Try cycling only the problematic zone and see if it still happens.

    Normally speaking, the internal stop ball closes off against flow, and if all components were flowing in the right direction, an oversized pump would actually cause this particular valve to bypass, even when not calling for heat, creating an over heat condition.

    Look closer...


    There was an error rendering this rich post.

  • Dave H_2
    Dave H_2 Member Posts: 557
    Check the circulator, not just the direction but what is the brand and model?
    Zone valve systems work best with flat curve circs - low head, high flow vs high head, low flow circs

    Dave H.
    Dave H
    Mark Eatherton
  • James D. Arch
    James D. Arch Member Posts: 19
    pump may be too close to zone valves??? residual flow yes.